1. Field of the Invention
This invention relates generally to transducer suspension systems and more particularly to a suspension system with integral electrical leads.
2. Description of Prior Art
Direct access storage devices (DASD), or disk drives, store information on concentric tracks of a rotatable magnetic recording disk. A magnetic head or transducer element is moved from track to track to record and read the desired information. Typically, the magnetic head is positioned on an air bearing slider which flies above the surface of the disk as the disk rotates. In some proposed disk drives, the slider (or carrier) rides on a liquid film or bearing on the disk. A suspension assembly connects the slider to a rotary or linear actuator. The suspension provides support for the slider.
The suspension must meet several requirements. The suspension must be flexible and provide a bias force in the vertical direction. This is necessary to provide a compensating force to the lifting force of the air bearing in order to keep the slider at the correct height above the disk. Also, vertical flexibility is needed to allow the slider to be loaded and unloaded away from the disk. Another requirement of the suspension is that it must provide a pivotal connection for the slider. Irregularities in operation may result in misalignment of the slider. The slider is able to compensate for these problems by pitching and/or rolling slightly to maintain the proper orientation necessary for the air bearing. Another requirement of the suspension is that it must be rigid in the lateral direction. This is needed to prevent the head from moving from side to side, which will result in the head reading the wrong track.
Disk drives have become smaller in size, and the recording track density has increased dramatically. This has necessitated the use of smaller and smaller heads and suspensions. The smaller size makes it more difficult to string individual wires along the suspension to the head. Recently, electrical leads (also known as conductors or lines) have been integrally formed directly into the suspension, by etching or deposition, in order to do away with the need to string separate wires. The electrical leads overlay a thin insulating layer which in turn overlays a metal support layer.
These etched leads are an integral part of the metal suspension body. The metal suspension can have a varying distance to the other metal parts of the arm assembly. For example, an IBM Ultrastar disk drive first publicly disclosed in September, 1998 has electrical leads which run along the suspension body, then veer outside and run along the outside periphery of the arm body. Electrical leads are fastened to the arm at a tab extension from the arm by means of a non-conductive adhesive. The metal support layer below the electrical leads is not continuous and has at least one gap section over the run of the electrical leads. The resulting suspension has a wide variance in distance between the electrical leads, metal support layer, suspension body, and arm along the run of the electrical leads. This distance variation will cause the electrical leads to be subject to signal interference and reduce the read signal bandwidth frequency.
This interference and bandwidth problem becomes greater as the data rates increase in frequency. There is a need for a suspension which solves these problems.